1. Field of the Invention
The subject invention generally pertains to reversible heat pump systems and more specifically to a system and method for managing the effective refrigerant charge while operating within or transitioning between various operating modes.
2. Description of Related Art
Compression refrigerant heat pumps with indoor and outdoor heat exchangers are operable selectively in heating and cooling modes. When the outdoor heat exchanger is air cooled (i.e., air cooled when the outdoor heat exchanger is condensing refrigerant therein), the heating mode may need to be periodically interrupted to defrost the outdoor heat exchanger by momentarily running the heat pump in a defrost mode.
Shifting from one operating mode to another can cause suction or discharge pressure faults and can cause slugs of liquid refrigerant to enter the compressor, which can damage the compressor. Consequently, there is a need for addressing the problems that occur when a heat pump changes modes of operation.